Don't make buttons with images too wide in wxMSW.

Don't make buttons with images too wide in wxMSW.

We used to increase the button size to the standard size first and then add
the extra padding the buttons with images. This resulted in too much padding
for the buttons with short text labels and images.

Instead, add the padding for the image first and only then increase the button
size to the standard one if still needed.

See #12924.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66892 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775